1. Field of the Invention
The present invention relates to a neutron detection apparatus capable of preventing occurrence of solid material in a thimble guide tube.
2. Description of the Background Art
In a BWR (Boiling Water Reactor), an in-reactor neutron monitor (hereinafter, referred to as an in-core monitor) is provided for recognizing the neutron flux distribution state in the reactor during operation of the reactor. The in-core monitor is inserted into the reactor core through an in-core monitor housing (hereinafter, referred to as an in-core housing) and a guide tube provided above the in-core housing.
A washing apparatus for the in-core housing and the guide tube includes: an outer box connected to the in-core monitor contained in the in-core housing and the guide tube provided above the in-core housing, and to an in-core flange forming a sheet portion; a piston shaft contained in the outer box so as to be movable up and down, and having a hollow portion through which washing drainage water flows down, on the inner circumferential side; a drive mechanism connected to the outer box and driving the piston shaft; and a discharge mechanism connected to the outer box and discharging the washing drainage water (for example, see Patent Document 1).
Patent Document 1: Japanese Laid-Open Patent Publication No. 59-220682
Such a conventional washing apparatus uses water for washing, and there is a problem that it is difficult to carry out the washing with water in a PWR (Pressurized Water Reactor).